Stereolithography

Stereolithography

mixture of propellant

stereolithography pattern

recording the information of a series of triangles

Product description: is a form of 3-D printing technology used for creating models, prototypes, patterns, and production parts in a layer by layer fashion using photopolymerization, a process by which light causes chains

Stereolithography (SL) is one of three
additive processes available at Vikled Molding. SL uses an ultraviolet laser
focused to a small point to draw on the surface of a liquid thermoset resin.
Where it draws, the liquid turns to solid. This is repeated in thin,
two-dimensional cross-sections that are layered to form complex
three-dimensional parts. SL provides the widest selection of material, best
feature resolution and smoothest surface finish. It works well for very small
parts and complex geometries during early prototyping.

Process

Quoting

When a 3D CAD model of a part has
been uploaded by a customer, it is moved into a scheduling and build queue. All
of the part files are downloaded and the geometry is analyzed for any potential
manufacturability issues. If any issues do arise, a dialog between a Vikled
Molding representative and the customer will take place to resolve the problem
before the actual build begins.

Build preparation

As the stereolithography
build prep begins, parts are digitally positioned onto the build platform and
the necessary support structures are strategically placed onto the part.
Automated supports are initially placed followed by supplemental supports done
manually to provide a comprehensive final support system. Because part features
are imaged on the surface of liquid, if the parts are not supported in the SL
process, they would float away or collapse during the build.

Build prep technicians then go through a layer-by-layer review of the build to
ensure that all of the features are adequately supported for a successful build
(With an average build height of 1 to 2 inches, for example, there would be
approximately 500 to 1,000 layers.) Once the review is complete, the
technicians will digitally create the required amount of copies required for a
particular order before it is ultimately sent to the SL machine.

Part production

The machine begins drawing the layers of the support
structures, followed by the part itself, with an ultraviolet laser aimed onto
the surface of a liquid thermoset resin. After a layer is imaged on the resin
surface, the build platform shifts down and a recoating bar moves across the
platform to apply the next layer of resin. The process is repeated layer by
layer until the build is complete.

Post build

The tray containing the newly built
parts is taken out of machine and into a lab where solvents are used to remove
any additional resins. When the parts are completely clean, the support
structures are manually removed. From there, parts undergo a UV-curing cycle to
fully solidify the outer surface of the part. The final step in the
stereolithography process is the application of any customer-specified finishes
— unfinished, natural finish (sanding of the supported surfaces to remove any
evidence of support), standard finish (400 grit matte finish with a grit
blaster in addition to sanding supported surfaces) and custom finishing
(ranging from colored paint to optically clear lenses to decals and lettering.)

SolventsStructures Finishing

Design Guidelines

Size

With our additive processes, we’re
able to deliver prototypes ranging from very small parts that meet extreme
tolerance demands to large parts with precise patterns. Maximum build size for
parts built by stereolithography is 29 in.
by 25 in. by 21 in. (736mm by 635mm
by 533mm).

Resolution

Vikled Molding excels in
high-quality precision parts that are available in three different SL
resolutions:

Normal Resolution:

Layer thickness of 0.004 in. with minimum feature size of 0.010 in.

High Resolution:

Layer thickness of 0.002 in. with minimum feature size of 0.004 in.

Micro Resolution:

Layer thickness of 0.001 in. with minimum feature size of 0.002 in.

Normal resolution

High resolution

Micro resolution

Tolerances

For a well-designed part, tolerances
in X/Y dimensions are ±0.002 in.
(0.05mm) for the first
inch plus ±0.001 in./in.
(0.001mm/mm) for each
additional inch. Z dimensions are ±0.005
in. (0.13mm)
for the first inch plus ±0.001 in./in.
(0.001mm/mm) for each
additional inch. Note that tolerances may change depending on part geometry.

Surface finishes

Dots, or standing “nibs,” remain
evident on the bottom of the part from the support structure remnants.

Natural finish:

Supported surfaces are sanded down
to eliminate the support nibs.

Standard finish:

Supported surfaces are sanded, and
the whole part is finely blasted for a consistent look. Note that the layers
are still present.

Unfinished

Natural

Standard

Secondary options

Custom finishing — a service only
offered within Vikled Molding — is a mix of science, technology and fine art
that can transform a part to your exact specifications. Custom finishes
include:

Soft-touch paint

Clear part finishing

Paint finishes

Chrome plating

Masking

Color matching

Decals/graphic

Texture

Special applications

In addition to our normal SL
processes, we offer a few special applications unique to Vikled Molding. Our
SLArmor process takes stereolithography to the next level by finishing off an
advanced ceramic-filled epoxy material from DSM Somos® (NanoTool™) with a metal
coating that gives parts the look, feel and strength of metal, but without the
weight. The combination of NanoTool’s extreme strength, rigidity and
temperature resistance with SLArmor’s nickel plating, takes strength, stiffness
and impact and temperature resistance to a degree previously unattainable in SL
parts. In fact, the composite nature of the process gives SLArmor a greater
strength-to-weight ratio than some metals.

Using the Vikled Molding microfluidic fabrication process can allow you to
dramatically shorten your development time for microfluidic devices of all
shapes and sizes. If you intend to injection mold your microfluidic product,
then the microfluidic fabrication process will allow you to design and test
most features that you will employ in your injectionmolded product. This
process eliminates the constraints created by the limitations of conventional
or mask-less photolithography. Our microfluidic fabrication process is a
modified form of high-resolution stereolithography that allows the creation of
any 3D object(s) through a process of stacking two-dimensional layers of 50
microns thickness (0.002 in.).
Stereolithography technology utilizes a liquid photopolymer that is polymerized
into a solid by the application of ultra-violet light from a laser.

SLArmor

Microfluidic fabrication

Equipment

Vikled Molding employs multiple
additive machines that offer large build sizes, accurate parts and quick
production times. Our stereolithography machines consists of Vipers, ProJets,
and iPros. In high-resolution (HR) mode, Vipers and ProJets can make parts with
extremely tiny features and crisp details, while in normal resolution (NR)
mode, they can build cost-effective parts very quickly. iPros have build
volumes that are truly huge at 29 in.
by 25 in. by 21 in. (736mm by 635mm
by 533mm), and
yet are still able to image highly detailed parts easily.